Expression and synthesis of insulin-like growth factor-binding proteins in human glioma cell lines.
We previously demonstrated the presence of insulin-like growth factors (IGFs) and IGF-receptors in human glioma cell lines derived from primary glioblastomas. The biological action of IGFs is modulated by specific IGF-binding proteins (IGFBP)-1 to -7. By means of polymerase chain reaction (PCR), we detected mRNA transcripts for IGFBP-1 in 42%, IGFBP-2 in 65%, IGFBP-3 in 97%, IGFBP-4 in 3%, IGFBP-5 in 74%, IGFBP-6 in 94% and IGFBP-7 in 87% of the glioma cell lines. The specificity of the PCR reaction was verified by direct sequencing of the PCR product. In addition, the content of the most prevalent IGFBP-3 was measured in conditioned medium from glioma cells by specific radioimmunoassay with levels ranging from < 1 to 620 ng/ml. Moreover, the presence of membrane-bound IGFBPs (44, 50 and 60 kDa) as well as IGF-II receptors was demonstrated by using 125I-labelled IGF-II as a ligand. In conclusion, IGFBPs may modulate the IGF-mediated effects in these cell lines.
Zumkeller
W
W
Department of Paediatrics, University Hospital Eppendorf, Germany.
Müller
D
D
Müller
S
S
Günther
C
C
Westphal
M
M
D000368:Aged; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D018969:Insulin-Like Growth Factor Binding Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm